<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <input type="text" value="张三" placeholder="提示文本 请输入姓名">
    <input type="password">
    <input type="checkbox" class="che">
    <select name="" id="">
        <option value="name1">张三</option>
        <option value="name2">李四</option>
        <option value="name3">王五</option>
    </select>
    <button>按钮</button>
</body>
<script>
    const inp = document.querySelector('input')
    inp.type = 'password'
    inp.value = '张坚'
    inp.placeholder = '请输入张坚的身高'

    const inp2 = document.querySelector('.che')
    inp2.checked = true

    const sel = document.querySelector('select option')
    sel.selected = true
</script>
</html>